变性木薯淀粉糊精的制备工艺及其性质研究

以木薯淀粉为原料,采用醇介质酸水解制备变性木薯淀粉糊精.通过正交试验确定了淀粉糊精的制备条件,并对此条件下得到的产品进行了性质研究.结果表明,该产品持水性比原淀粉大,吸湿性较强,感官及其理化特性符合麦芽糖标准,酸解淀粉糊精的粘度与原淀粉相比数值下降,酸处理制备的糊精粒子微观结构无明显变化.     

Manganese oxide embedded graphene nanohybrid for pH-universal electrochemical overall water splitting

Efficient non-noble metal bifunctional electrocatalysts for overall water splitting in pH universal is highly desired in application. Herein, MnO₂/graphene composition are applied as efficient electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in pH-universal electrolytes with the help of plasma dc arc method. The couple of MnO₂ and graphene highly benefits to the H₂O, H⁺ and OH⁻ absorption respectively. The defects and stable Mn³⁺ contribute to the transfer of electron and charge. The low overpotentials and small Tafel slopes reveal attractive activities of HER and OER. The good electrocatalytic performances are attributed to the synergistic effect and abundant heterogeneous interfaces in MnO₂/graphene. These can offer rich electroactive sites and accelerate electron transfer. Thus, it may provide facile route for developing nonprecious electrocatalysts of water splitting.     

柚子酸奶的研究

以柚子汁和脱脂奶粉为主要原料,研究柚子酸奶的生产工艺.实验确定了袖子汁添加量10%、白砂糖9%、接种量7%,发酵时间4.5h、杀茵温度90℃、杀菌时间10min;复合稳定剂种类与配比为:黄原胶0.03%、羧甲基纤维素钠(CMC-Na)0.08%、卡拉胶0.005%.产品具有柚子和酸乳所特有的香气,爽滑细腻,既营养又保健,有着广阔的市场前景.     

Effect of tea polyphenols on the physical and chemical characteristics of dried-seasoned squid (Dosidicus gigas) during storage

The effects of tea polyphenols (TP) dip treatment on the physical and chemical characteristics of dried-seasoned squid (Dosidicus gigas) during storage at 25 °C were assessed. After the storage, the b* value increased significantly, while the free amino acids (FAA) including Ser, Gly, Arg, Tyr and Lys, and the dominant reducing sugar (RS), lactose, decreased remarkably, which revealed the occurrence of browning reaction in dried-seasoned squid. The progressive conversion of trimethylamine oxide (TMAO) and production of thiobarbituric acid (TBA) and total volatile basic nitrogen (TVB-N) were found during the entire period of storage. Furthermore, the advantages of reducing moisture loss, inhibiting oxidation of lipids, depressing TMAO breakdown and TVB-N accumulation were observed, while the browning reaction exhibited no significant decrease for the TP samples. These results indicated that the addition of TP could maintain quality of dried-seasoned squid.     

蛋白酶水解马氏珠母贝肉对镉解离效果的研究

为了考查蛋白酶水解马氏珠母贝肉过程中对镉解离效果的影响,从木瓜蛋白酶、胰蛋白酶、精制中性蛋白酶、胃蛋白酶和枯草杆菌蛋白酶5种蛋白酶中筛选镉解离效果最好的酶,分别进行单一酶解试验和双酶复合酶解试验.以镉解离度和水解得率为指标,利用响应面法优化酶解条件.结果表明:枯草杆菌蛋白酶为最适蛋白酶,镉的解离度为75.57％,胰蛋白酶的效果次之,镉解离度为70.66％.用枯草杆菌蛋白酶进行单一酶解试验,最佳的酶解条件为时间5h,温度65℃,添加量4 700 U/g,液固比5∶1(V∶m),pH值7.5时,水解得率为87.43％,酶解镉解离度达到81.87％;用枯草杆菌蛋白酶与胰蛋白酶以活力比为3∶1组合,水解效果和镉解离度均最好.双酶复合酶解优化试验得到的最佳水解条件为时间5h,温度50℃,添加量5 700 U/g,pH值7.0,液固比4∶1(V∶m),水解得率为90.93％,镉解离度达到85.52％,比单一酶酶解效果更好.     

“数字信号处理”中重叠保留法的证明

重叠保留法是计算一个短序列与一个无限长序列线性卷积的有效方法。就我们所知，多数《数字信号处理》教材详细叙述了重叠保留法的步骤，有些教材还从线性卷积与循环卷积的关系出发给出了重叠保留法的原理，笔者认为这种解释不够清楚、也不够严谨。本文给出了一个较为严谨而准确的证明。     

Thermogravimetric analysis of chitosan

The thermal degradation of chitosan at different heating rates B in nitrogen was studied by thermogravimetric analysis. The results indicate that the thermal degradation of chitosan in nitrogen is a one‐step reaction. The degradation temperatures increase with B. Experimentally, the initial degradation temperature (T₀) is (1.049B + 326.8)°C; the temperature at the maximum degradation rate, that is, the peak temperature on a differential thermogravimetry curve (T_p), is (1.291B + 355.2)°C; and the final degradation temperature (T_f) is (1.505B + 369.7)°C. The degradation rates at T_p and T_f are not affected by B, and their average values are 50.17% and 72.16%, respectively, the maximum thermal degradation reaction rate, that is, the peak height on a differential thermogravimetry curve (R_p), increases with B. The relationship between B and R_p is R_p = (1.20B + 2.44)% min^?1. The thermal degradation kinetic parameters are calculated with the Ozawa–Flynn–Wall method. The reaction activation energy (E) and frequency factor (A) change with an increasing degree of decomposition, and the variable trends of the two kinetic parameters are similar. The values of E and A increase remarkably during the initial stage of the reaction, then keep relatively steady, and finally reach a peak during the last stage. The velocity constants of the thermal degradation vary with the degree of decomposition and increase with the reaction temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

基于LabVIEW的检测报告生成和打印设计

为了反映系统检测结果,需要将检测结论以特定格式的报告形式进行输出,以风量罩自动检测系统为例,使用LabVIEW图形化编程技术开发自动检测仪器软件,基于报告生成工具包(report generation toolkit),应用全局变量,通过ActiveX技术将Microsoft Excel开发环境集成起来,设计了自动生成专业检测报告程序模块,该程序能够自动记录系统检测过程中生成的结果,并生成基于指定格式的Excel检测报告,最后通过Query Available Printers,在软件查询功能下搜索可用打印机实现检测报告打印输出。     

超长、大管径精密螺纹套管专用数控套车机床研究

介绍了一种用于管长12 m、管径φ200～550 mm的多头、变螺距精密螺纹套管加工的专用数控套车机床的工作原理、基本组成.重点分析了该机床数控径向切削进给的实现方法,以及多刀同时切削多头螺纹的技术实现,给出了工程应用实例.     

HCKX320D高速走丝线切割机异面加工分析

描述了电火花线切割异面加工的主要优点和异面加工的实现机理,结合HCKX320D机床进行异面加工试验,分析了锥度切割误差产生的原因及线切割锥度加工参数的设定对工件的影响,为异面加工提供有效的理论依据.